Interlayer bonding sheet for multilayer board and preparation method and application thereof

文档序号：887963 发布日期：2021-03-23 浏览：6次中文

阅读说明：本技术 一种多层板用层间粘结片及其制备方法和应用 (Interlayer bonding sheet for multilayer board and preparation method and application thereof ) 是由苏民社周如金梁伟郭浩勇于 2019-09-04 设计创作，主要内容包括：本发明提供一种多层板用层间粘结片及其制备方法和应用,所述多层板用层间粘结片包括PTFE基片,以及粘结于所述PTFE基片表面的介电树脂层；所述PTFE基片为表面经过等离子体处理的PTFE基片,所述PTFE基片的表面处理深度为5～15nm。所述PTFE基片表面经过等离子体处理后实现了功能化改性,润湿性显著提高,能够与介电树脂层发生高强度的稳定粘结。本发明所述多层板用层间粘结片通过表面经过等离体子处理的PTFE基片与介电树脂层的协同配合,具有优异的介电性能、流动性以及粘结强度,而且粘结稳定性高,可以充分满足多层板的信号高频化需求以及稳定性、可靠性需求。(The invention provides an interlayer bonding sheet for a multilayer board, and a preparation method and application thereof, wherein the interlayer bonding sheet for the multilayer board comprises a PTFE substrate and a dielectric resin layer bonded on the surface of the PTFE substrate; the PTFE substrate is a PTFE substrate with a plasma-treated surface, and the surface treatment depth of the PTFE substrate is 5-15 nm. The surface of the PTFE substrate is subjected to plasma treatment to realize functional modification, the wettability is obviously improved, and the PTFE substrate can be stably bonded with a dielectric resin layer with high strength. The interlayer bonding sheet for the multilayer board has excellent dielectric property, fluidity and bonding strength through the synergistic matching of the PTFE substrate and the dielectric resin layer, the surface of which is subjected to plasma treatment, has high bonding stability, and can fully meet the signal high-frequency requirement, stability and reliability requirement of the multilayer board.)

1. An interlayer bonding sheet for a multilayer board, comprising a PTFE substrate, and a dielectric resin layer bonded to the surface of the PTFE substrate;

the PTFE substrate is a PTFE substrate with a plasma-treated surface, and the surface treatment depth of the PTFE substrate is 5-15 nm.

2. The interlayer bonding sheet for a multilayer sheet according to claim 1, wherein the contact angle of the PTFE substrate is 84 to 98 °.

3. The interlayer bonding sheet for a multilayer sheet according to claim 1 or 2, comprising a PTFE substrate, and dielectric resin layers bonded to the upper and lower surfaces of the PTFE substrate.

4. The interlayer bonding sheet for a multilayer sheet according to any one of claims 1 to 3, wherein the PTFE substrate has a thickness of 0.3 to 1.5 mm;

preferably, the PTFE substrate is glass cloth with a PTFE layer on the surface;

preferably, the glass cloth is electronic-grade glass cloth or once-desized glass cloth;

preferably, the PTFE substrate is obtained by soaking glass cloth in PTFE emulsion, drying and sintering;

preferably, the PTFE emulsion is a PTFE emulsion containing a powdered filler;

preferably, the powder filler is selected from any one or a combination of at least two of silicon dioxide, titanium dioxide, strontium titanate, barium titanate, boron nitride, aluminum nitride, silicon carbide, alumina, glass fiber, polytetrafluoroethylene, polyphenylene sulfide or polyether sulfone, and is further preferably silicon dioxide;

preferably, the median particle diameter of the powder filler is 1 to 15 μm, and more preferably 1 to 10 μm.

5. The interlayer bonding sheet for multilayer boards according to any one of claims 1 to 4, wherein the thickness of the dielectric resin layer is 5 to 60 μm, preferably 20 to 50 μm;

preferably, the raw materials for preparing the dielectric resin layer comprise the following components in parts by weight: 20-70 parts of polymer matrix material, 0-70 parts of powder filler and 1-3 parts of initiator;

preferably, the polymer matrix material is selected from any one or a combination of at least two of polybutadiene, polyisoprene, butadiene-styrene copolymer, polyphenylene oxide or ethylene propylene rubber;

preferably, the initiator is an organic peroxide initiator;

preferably, the median particle diameter of the powder filler is 1 to 15 μm, and more preferably 1 to 10 μm.

6. A method for producing an interlayer bonding sheet for a multilayer sheet according to any one of claims 1 to 5, comprising the steps of:

(1) treating the PTFE substrate by using plasma to obtain the PTFE substrate after surface plasma treatment;

(2) and (2) coating a dielectric resin layer on the PTFE substrate subjected to the surface plasma treatment obtained in the step (1), and curing to obtain the interlayer bonding sheet for the multilayer board.

7. The method according to claim 6, wherein an atmosphere of the plasma treatment in the step (1) is selected from He, Ne and O₂、H₂、N₂、Ar、CO₂、SO₂、NH₃、CH₄Or water vapor or a combination of at least two of the foregoing;

preferably, the plasma treatment of step (1) is performed by a low-temperature plasma generation device;

preferably, the voltage of the plasma treatment in the step (1) is 500-10000V;

preferably, the plasma treatment time in the step (1) is 5-600 s, and more preferably 50-600 s;

preferably, the vacuum degree of the plasma processing system in the step (1) is 133-1333 Pa;

preferably, the radio frequency power of the plasma treatment in the step (1) is 1-5 kW;

preferably, the coating method in the step (2) is roller coating;

preferably, the curing temperature in the step (2) is 160-250 ℃, and further preferably 180-230 ℃;

preferably, the curing time in the step (2) is 1-4 h, and more preferably 1.5-3 h.

8. The preparation method according to claim 6 or 7, characterized in that it comprises in particular the steps of:

(1) placing the cleaned PTFE substrate in a low-temperature plasma generator for surface plasma treatment in a treatment atmosphere selected from He, Ne and O₂、H₂、N₂、Ar、CO₂、SO₂、NH₃、CH₄Or any one or the combination of at least two of water vapor, the processing voltage is 500-10000V, the vacuum degree of a processing system is 133-1333 Pa, the radio frequency power of the processing is 1-5 kW, and the processing time is 5-600 s, so that the PTFE substrate after surface plasma processing is obtained;

(2) and (2) coating a dielectric resin layer on the PTFE substrate subjected to the surface plasma treatment obtained in the step (1), and curing at 160-250 ℃ for 1-4 h to obtain the interlayer bonding sheet for the multilayer board.

9. A multilayer board comprising at least two PTFE double-sided circuit boards, and the interlayer bonding sheet for multilayer boards according to any one of claims 1 to 5 interposed between the two PTFE double-sided circuit boards.

10. An electronic device, characterized in that it comprises a multilayer board according to claim 9.

Technical Field

The invention belongs to the technical field of copper-clad plates, and particularly relates to an interlayer bonding sheet for a multilayer plate, and a preparation method and application thereof.

Background

The rapid development of information industry, advanced communication equipment and technology has brought new performance requirements for high-frequency electronic equipment widely used in the communication field, and signal processing and transmission power of electronic equipment is greatly increased, moving from MHz to GHz, and therefore, electronic circuit substrates for signal transmission are inevitably subject to a shift to high-frequency and high-speed characteristics. In the high-frequency and high-speed development process of electronic circuit base materials, the key point is that a material with excellent electrical performance is selected, the dielectric constant and the dielectric loss tangent of Polytetrafluoroethylene (PTFE) are small, and the Polytetrafluoroethylene (PTFE) is good in aging resistance and high and low temperature resistance and is an ideal high-frequency base material.

In recent years, the electronic industry based on microelectronics has driven the development of miniaturization, multi-functionalization and high performance of electronic products, and the miniaturization, the functionalization and the multilayering of printed circuit boards as essential components for circuit interconnection are also required. However, since PTFE resin has low surface energy and almost no fluidity and adhesiveness, and is difficult to be used as an adhesive material between layers of a multilayer board, the search for an interlayer adhesive material for a multilayer printed circuit board having excellent electrical properties is very important for the development of the entire circuit board industry.

CN101220160 discloses a prepreg applied to a printed circuit multilayer board, which comprises a reinforcing material and a resin composition, wherein the reinforcing material is glass fiber paper, and the resin composition comprises the following components in parts by weight: 20-84 parts of resin, 0-35 parts of filler, 0.01-0.3 part of curing accelerator and 10-45 parts of solvent; wherein the resin is one or more of cyanate resin, benzoxazine resin, bismaleimide resin, polyimide resin and polytetrafluoroethylene resin. The prepreg can be used as a material for processing a multilayer PCB, solves the problems of layering, board explosion, resin shrinkage and the like of the multilayer PCB after cold and hot impact, and has good reliability and low cost.

CN102051021A discloses a prepreg applied to a printed circuit board for filling a nano molecular sieve and a preparation method thereof, wherein the prepreg comprises a reinforcing material and a resin composition, the reinforcing material is glass fiber paper or glass fiber cloth, and the resin composition is a mixture of 30-72 parts of resin, 0-10 parts of filler, 0.01-0.5 part of curing accelerator and 5-50 parts of solvent; wherein the resin composition is one or more of epoxy resin, epoxy modified resin, cyanate ester, benzoxazine, bismaleimide, polyimide, polytetrafluoroethylene and phenolic resin, and the filler is a nano titanium silicalite molecular sieve or a mesoporous molecular sieve. The prepreg has low dielectric constant, high glass transition temperature and low thermal expansion coefficient, and can meet the requirements of advanced electronic equipment.

In the process of developing a PTFE multilayer board to higher performance and higher frequency, researchers find that a prepreg based on thermosetting resin such as epoxy and the like has good bonding performance, but has high dielectric constant and dielectric loss tangent, insufficient high-frequency characteristics and can not meet the requirement of signal high-frequency; the polyolefin resin has low dielectric loss tangent but poor tolerance, and is difficult to meet the process requirement and the use requirement of the manufacture of the printed circuit board; although the prepreg prepared by using the fluorine-containing resin overcomes the defects of partial dielectric property and tolerance, the bonding property of the fluorine resin and a film material is poor, and the phenomena of layering, foaming and the like occur at high temperature, so that the obtained PTFE multilayer board has poor bonding heat-resistant reliability and cannot meet the subsequent application requirements.

Therefore, it is a research focus in the field to develop an interlayer adhesive material for a multi-layer board with good adhesive property, heat resistance and reliability to satisfy various properties and application requirements of a high frequency multi-layer printed circuit board.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an interlayer bonding sheet for a multilayer board, a preparation method and application thereof, wherein the interlayer bonding sheet for the multilayer board comprises a PTFE substrate and a dielectric resin layer bonded on the surface of the PTFE substrate; the PTFE substrate generates free radicals and active sites after plasma surface treatment, so that the functional modification of the surface of the PTFE substrate is realized, and the bonding property is obviously improved. The interlayer bonding sheet for the multilayer board has excellent dielectric property, fluidity and bonding strength through the cooperative matching of the PTFE substrate and the dielectric resin layer, the surface of which is subjected to plasma treatment, and can meet the signal high-frequency requirement, stability and reliability requirement of the multilayer board.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides an interlayer bonding sheet for a multilayer sheet, comprising a PTFE substrate, and a dielectric resin layer bonded to a surface of the PTFE substrate.

The PTFE substrate is a PTFE substrate with a plasma-treated surface, the surface treatment depth of the PTFE substrate is 5-15 nm, such as 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm or 14nm, and the specific values therebetween are limited by space and for the sake of brevity, and the present invention is not exhaustive list of the specific values included in the range.

The interlayer bonding sheet for the multilayer board comprises a PTFE substrate with the surface subjected to plasma treatment and a dielectric resin layer bonded on the PTFE substrate, wherein the PTFE substrate and the dielectric resin layer have excellent dielectric properties, low dielectric constant and dielectric loss tangent and sufficient high-frequency characteristics, and can meet the electrical property requirements of the multilayer board.

The plasma surface treatment refers to a physical or chemical action process of plasma of non-polymerizable gas on the surface of a high molecular material. The PTFE material on the PTFE substrate has the characteristics of high crystallinity, low surface energy and difficult wetting,meanwhile, the difference between the solubility parameter and the solubility parameter of a common adhesive is large, and the interfaces are difficult to diffuse mutually at will, so the adhesive is a difficult-to-adhere material. The PTFE substrate of the present invention is processed by passing various gases (e.g., He, Ne, O) during plasma treatment₂、H₂、N₂、Ar、CO₂、SO₂、NH₃、CH₄Or any one of water vapor or a combination of at least two of water vapor) to activate and functionalize the PTFE surface; the dissipation process of the energy is the process of obtaining modification on the surface of the PTFE substrate; the PTFE substrate generates free radicals on the surface through plasma treatment, and the formed active sites can continuously react with gas components in plasma to cause a series of surface modification. After the surface of the PTFE substrate is treated by plasma, the reaction activity is enhanced, the PTFE substrate can be stably bonded with a dielectric resin layer with high strength, the heat resistance and the high-temperature reliability are high, and the manufacturing process requirement and the subsequent application requirement of a multilayer printed circuit board can be met.

In addition, the dielectric resin layer in the interlayer bonding sheet for the multilayer board has excellent dielectric property and heat resistance, good chemical resistance and mechanical property, toughness capable of meeting the process requirement of the multilayer board, good fluidity and bonding property, strong interlayer bonding force between circuit boards and high bonding stability.

In conclusion, the interlayer bonding sheet for the multilayer board provided by the invention has excellent dielectric property, fluidity and bonding strength through the synergistic cooperation of the PTFE substrate and the dielectric resin layer, the surface of which is subjected to plasma treatment, and can fully meet the signal high-frequency requirement, stability and reliability requirement of the multilayer board.

When the surface treatment depth of the PTFE substrate is within the range of 5-15 nm, the PTFE substrate and the dielectric resin layer have the best bonding strength and high bonding stability. When the plasma treatment depth is less than 5nm, the plasma etching depth is shallow, the surface area is low, and ideal bonding cannot be formed; when the plasma treatment depth is more than 15nm, the treatment is excessive, the surface activation is weakened, the improvement of wettability is affected, and an ideal bond cannot be formed.

Preferably, the contact angle of the PTFE substrate is 84 to 98 °, such as 85 °, 86 °, 87 °, 88 °, 89 °, 90 °, 91 °, 92 °, 93 °, 94 °, 95 °, 96 °, or 97 °, and specific values therebetween, for brevity and clarity, are not exhaustive of the specific values included in the ranges.

The contact angle of the PTFE substrate is 84-98 degrees, if the contact angle is larger than 98 degrees, the wettability of the PTFE substrate is poor, and the PTFE substrate is difficult to be tightly adhered to the dielectric resin layer; if the contact angle is less than 84 °, the surface is excessively treated with plasma, which reduces the surface activation, lowers the wettability of the substrate surface, and prevents high-strength adhesion with the dielectric resin layer.

Preferably, the interlayer bonding sheet for a multilayer board includes a PTFE substrate, and dielectric resin layers bonded to upper and lower surfaces of the PTFE substrate.

Preferably, the PTFE substrate has a thickness of 0.3 to 1.5mm, such as 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, or 1.4mm, and specific values therebetween, not to be limited by space and for the sake of brevity, the present invention is not exhaustive of the specific values included in the ranges.

Preferably, the PTFE substrate is glass cloth with a PTFE layer on the surface.

Preferably, the glass cloth is electronic-grade glass cloth or once-desized glass cloth; for example, the electronic grade glass cloth may be 1037, 106, 1080, 1078, and the like.

Preferably, the PTFE substrate is obtained by soaking glass cloth in PTFE emulsion, drying and sintering.

The PTFE emulsion of the present invention means an aqueous dispersion containing a PTFE resin.

Preferably, the PTFE emulsion is a PTFE emulsion containing a powdered filler.

Preferably, the powder filler is selected from any one or a combination of at least two of silica, titanium dioxide, strontium titanate, barium titanate, boron nitride, aluminum nitride, silicon carbide, alumina, glass fiber, polytetrafluoroethylene, polyphenylene sulfide or polyether sulfone, and more preferably is silica.

Illustratively, the silica may be any one of crystalline silica, fused silica, or spherical silica, or a combination of at least two thereof.

Preferably, the powder filler has a median particle diameter of 1 to 15 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm or 14 μm, and specific values therebetween, which are not intended to limit the disclosure and for the sake of brevity, the present invention is not exhaustive of the specific values included in the range, and more preferably 1 to 10 μm.

Preferably, the thickness of the dielectric resin layer is 5-60 μm, such as 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 17 μm, 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, 33 μm, 35 μm, 37 μm, 40 μm, 42 μm, 45 μm, 48 μm, 50 μm, 53 μm, 55 μm, 57 μm or 59 μm, and the specific dot values therebetween are limited to the dot value range and for the sake of brevity, the invention does not exhaust the specific dot values included in the range, and more preferably 20-50 μm.

Preferably, the raw materials for preparing the dielectric resin layer comprise the following components in parts by weight: 20-70 parts of polymer matrix material, 0-70 parts of powder filler and 1-3 parts of initiator.

Preferably, the polymer matrix material is selected from any one of polybutadiene, polyisoprene, butadiene-styrene copolymer, polyphenylene oxide or ethylene propylene rubber or a combination of at least two of the same.

The resin compositions disclosed in the prior art to meet the above requirements can be used to prepare the dielectric resin layer of the present invention. Such prior art includes, by way of example and not limitation: CN106867173A discloses a composite material, comprising: (1) 20-70 parts of a thermosetting mixture comprising: (A) a thermosetting resin based on polybutadiene having a molecular weight of 11000 or less and containing 60% or more of vinyl groups or a copolymer resin of polybutadiene and styrene, which is composed of hydrocarbon elements; and (B) an ethylene-propylene rubber which is solid at room temperature and has a weight average molecular weight of more than 10 ten thousand and less than 15 ten thousand and a number average molecular weight of more than 6 ten thousand and less than 10 ten thousand; (2) 10-60 parts of glass fiber cloth; (3) 0-70 parts of powder filler; (4) 1-3 parts of curing initiator. CN102161823A discloses a composite material, which comprises more than one vinyl liquid resin with molecular weight less than 10000 and polar functional groups, a polyphenylene oxide resin with molecular weight less than 5000 and molecular end with unsaturated double bond, glass fiber cloth, powder filler, flame retardant and curing initiator. CN101643565B discloses a composite material, which comprises a resin containing more than 60% of vinyl and consisting of hydrocarbon elements with molecular weight of less than 11000, a medium-low molecular weight solid styrene-based resin with unsaturated double bonds, glass fiber cloth, powder filler, flame retardant and curing initiator. CN102807658A discloses a polyphenylene ether resin composition component comprising a functionalized polyphenylene ether resin, a crosslinking curing agent and an initiator; the functionalized polyphenylene ether resin is polyphenylene ether resin with a number average molecular weight of 500-5000 and an unsaturated double bond at the molecular terminal, and the crosslinking curing agent is olefin resin with a number average molecular weight of 500-10000 and containing 10-50 wt% of styrene structure, and the molecule of the resin contains a 1, 2-bit addition butadiene structure. CN102993683A discloses a modified polyphenylene ether resin, an organic silicon compound containing an unsaturated double bond, and the like.

In the raw material for preparing the polymer matrix material of the present invention, the content of the polymer matrix material may be 22 parts by weight, 25 parts by weight, 28 parts by weight, 30 parts by weight, 32 parts by weight, 35 parts by weight, 38 parts by weight, 40 parts by weight, 42 parts by weight, 45 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 55 parts by weight, 58 parts by weight, 60 parts by weight, 62 parts by weight, 65 parts by weight, 68 parts by weight, 69 parts by weight, or the like.

The content of the powder filler may be 2 parts by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 68 parts by weight, or the like.

The initiator may be present in an amount of 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, 2.8 parts by weight, 2.9 parts by weight, or the like.

As a preferred embodiment of the present invention, the polymer matrix material comprises: (A) a thermosetting resin based on polybutadiene or a butadiene-styrene copolymer having a molecular weight of 11000g/mol or less (e.g., 10500g/mol, 10000g/mol, 9800g/mol, 9500g/mol, 9300g/mol, 9000g/mol, 8800g/mol, 8500g/mol, 8300g/mol, or 8000 g/mol), containing 60% or more (e.g., 61%, 63%, 65%, 67%, 69%, 71%, 73%, 75%, or 77% or the like) vinyl groups and composed of hydrocarbon elements, and comprising (B) a thermosetting resin having a weight average molecular weight of 100000 to 150000g/mol (e.g., 105000g/mol, 110000g/mol, 115000g/mol, 120000g/mol, 125000g/mol, 130000g/mol, 135000g/mol, 140000g/mol, or 145000g/mol, or the like), An ethylene-propylene rubber which is solid at room temperature and has a number-average molecular weight of 60000 to 100000g/mol (e.g., 65000g/mol, 70000g/mol, 75000g/mol, 80000g/mol, 85000g/mol, 90000g/mol, or 95000 g/mol).

The molecular weight, the weight average molecular weight and the number average molecular weight data are obtained by testing according to the method specified in GB/T21863-2008 standard, and are measured by gel permeation chromatography based on polystyrene calibration.

Preferably, the initiator is an organic peroxide initiator.

Illustratively, the organic peroxide initiator includes benzoyl peroxide, dicumyl peroxide, or t-butyl peroxybenzoate, and the like.

Illustratively, the silica may be crystalline silica, fused silica, or spherical silica, among others.

In another aspect, the present invention provides a method for producing an interlayer bonding sheet for a multilayer sheet according to the first aspect, comprising the steps of:

(1) treating the PTFE substrate by using plasma to obtain the PTFE substrate after surface plasma treatment;

Preferably, the atmosphere of the plasma treatment in the step (1) is selected from He, Ne and O₂、H₂、N₂、Ar、CO₂、SO₂、NH₃、CH₄Or water vapor or a combination of at least two thereof.

Preferably, the plasma treatment of step (1) is performed by a low-temperature plasma generation device.

Preferably, the voltage of the plasma treatment in step (1) is 500-10000V, such as 550V, 600V, 700V, 800V, 900V, 1000V, 1500V, 2000V, 3000V, 4000V, 5000V, 6000V, 7000V, 8000V, 9000V or 9500V, and the specific values therebetween are not exhaustive, and for the sake of brevity and clarity, the invention is not intended to be exhaustive.

Preferably, the plasma treatment time in step (1) is 5-600 s, such as 6s, 8s, 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 120s, 150s, 180s, 200s, 220s, 250s, 280s, 300s, 320s, 350s, 380s, 400s, 420s, 450s, 480s, 500s, 520s, 550s, 570s, or 590s, and the specific point values between the above-mentioned point values are limited to space and are not exhaustive for the sake of brevity.

Preferably, the system vacuum degree of the plasma processing in step (1) is 133-1333 Pa, such as 135Pa, 140Pa, 150Pa, 170Pa, 190Pa, 200Pa, 230Pa, 250Pa, 280Pa, 300Pa, 350Pa, 400Pa, 500Pa, 600Pa, 700Pa, 800Pa, 900Pa, 1000Pa, 1100Pa, 1200Pa or 1300Pa, and specific point values therebetween are limited to space and for brevity, and the invention does not exhaust the specific point values included in the range.

Preferably, the rf power of the plasma treatment in step (1) is 1 to 5kW, such as 1.2kW, 1.4kW, 1.6kW, 1.8kW, 2kW, 2.2kW, 2.5kW, 2.8kW, 3kW, 3.2kW, 3.5kW, 3.8kW, 4kW, 4.2kW, 4.5kW, 4.7kW, or 4.9kW, and the specific points therebetween are limited to space and for simplicity, and the invention is not exhaustive.

Preferably, the coating method in the step (2) is roll coating.

Preferably, the curing temperature in step (2) is 160 to 250 ℃, such as 165 ℃, 170 ℃, 175 ℃, 180 ℃, 185 ℃, 190 ℃, 195 ℃, 200 ℃, 205 ℃, 210 ℃, 215 ℃, 220 ℃, 225 ℃, 230 ℃, 235 ℃, 240 ℃ or 245 ℃, and more preferably 180 to 230 ℃.

Preferably, the curing time in the step (2) is 1 to 4 hours, such as 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, 2.3 hours, 2.5 hours, 2.8 hours, 3 hours, 3.5 hours or 3.8 hours, and the like, and further preferably 1.5 to 3 hours.

Preferably, the preparation method specifically comprises the following steps:

(1) placing the cleaned PTFE substrate in a low-temperature plasma generator for surface plasma treatment in a treatment atmosphere selected from He, Ne and O₂、H₂、N₂、Ar、CO₂、SO₂、NH₃、CH₄Or any one or the combination of at least two of water vapor, the processing voltage is 500-10000V, the vacuum degree of a system for processing is 133-1333 Pa, the radio frequency power for processing is 1-5 kW, and the processing time is 5-600 sAnd obtaining the PTFE substrate after surface plasma treatment.

(2) And (2) coating a dielectric resin layer on the PTFE substrate subjected to the surface plasma treatment obtained in the step (1), and curing at 160-250 ℃ for 1-4 h to obtain the interlayer bonding sheet for the multilayer board.

In another aspect, the present invention provides a multilayer board comprising at least two PTFE double-sided circuit boards, and an interlayer bonding sheet for a multilayer board according to the first aspect interposed between the two PTFE double-sided circuit boards.

In another aspect, the present invention provides an electronic device including the multilayer board as described above.

Compared with the prior art, the invention has the following beneficial effects:

the interlayer bonding sheet for the multilayer board comprises a PTFE substrate with the surface subjected to plasma treatment and a dielectric resin layer bonded on the PTFE substrate, wherein the PTFE substrate and the dielectric resin layer have excellent dielectric properties, low dielectric constant and dielectric loss tangent and sufficient high-frequency characteristics, and can meet the electrical property requirements of the multilayer board; after the surface of the PTFE substrate is subjected to plasma treatment, the wettability is obviously improved, the PTFE substrate can be stably bonded with a dielectric resin layer at high strength, the heat resistance and the high-temperature reliability are high, and the manufacturing process requirements and the subsequent application requirements of a multilayer printed circuit board can be met; the dielectric resin layer has good fluidity and bonding property, and can ensure strong interlayer bonding force and high bonding stability between circuit boards. Therefore, the interlayer bonding sheet for the multilayer board provided by the invention has excellent dielectric property, fluidity and bonding strength through the synergistic matching of the PTFE substrate with the surface treated by the plasma body and the dielectric resin layer, the multilayer board containing the interlayer bonding sheet for the multilayer board has no delamination and foaming phenomenon at 288 ℃ in a high-temperature environment, the bonding stability is high, and the signal high-frequency requirement, the stability and the reliability requirement of the multilayer board can be fully met.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The experimental materials used in the examples and comparative examples of the present invention were as follows:

(1) a PTFE substrate: soaking 1078 type electronic grade glass cloth in PTFE emulsion (average particle size of PTFE is 0.1-0.5 μm) at normal temperature, drying at 150 deg.C, and sintering at 360 deg.C for 30min to obtain the final product; such materials are available from dupont, usa.

(2) Dielectric resin treatment liquid I: 30 parts by weight of ethylene-propylene rubber (number average molecular weight 80000g/mol, lion chemical company, usa), 40 parts by weight of polybutadiene (molecular weight 3200g/mol, japan caoda corporation), 30 parts by weight of silica (median particle diameter 5 μm, new materials of Jiangsu Union Ltd.), and 2 parts by weight of benzoyl peroxide (Shanghai Kanglang Biotech Co., Ltd.) were dissolved in 50 parts by weight of xylene and mixed uniformly to obtain a dielectric resin treatment liquid I;

dielectric resin treatment liquid II: 25 parts by weight of ethylene-propylene rubber (number average molecular weight 80000g/mol, lion chemical company, usa), 35 parts by weight of butadiene-styrene copolymer (number average molecular weight 4500g/mol, sartomer company, usa), 10 parts by weight of polyphenylene ether (weight average molecular weight 1700g/mol, SABIC company, usa), 30 parts by weight of silica (median particle diameter 10 μm, Jiangsu Union Rui New Material Co., Ltd.) and 2 parts by weight of benzoyl peroxide (Shanghai Kanglang Biotech Co., Ltd.) were dissolved in 50 parts by weight of xylene and mixed uniformly to obtain dielectric resin treatment liquid II.

Dielectric resin treatment liquid III: 25 parts by weight of a butadiene-styrene copolymer (number average molecular weight 8900g/mol, Saedoma, USA), 15 parts by weight of polybutadiene (number average molecular weight 3200g/mol, Nippon Caoda corporation), 30 parts by weight of polyphenylene ether (weight average molecular weight 1700g/mol, SABIC), 30 parts by weight of silica (median diameter 10 μm, Jiangsonirui New Material Co., Ltd.) and 2 parts by weight of benzoyl peroxide (Shanghai Kanglang Biotech Co., Ltd.) were dissolved in 50 parts by weight of xylene and mixed uniformly to obtain a dielectric resin treatment liquid III.

(3) Low-temperature plasma generating device: plasma processor model CD1200 from europlas corporation, belgium.

(4) Self-made PTFE double-sided circuit board.

Example 1